1. Field of the Invention
This invention relates to a method and an apparatus for reproducing information from a recording disc such as a DVD (digital video disc), a CD (compact disc), or a CD-ROM (compact disc read only memory). Also, this invention relates to a method and an apparatus for recording information on a recording disc. Furthermore, this invention relates to a recording disc.
2. Description of the Related Art
According to a conceivable system (which is not prior art to this invention) for copyright protection regarding main information on a recording disc, copyright management information is scrambled, and the scrambled version of the copyright management information is recorded on a legitimate disc. Also, main information is recorded on the legitimate disc. The copyright management information is designed so that a portion thereof forms a playback permission key. Thus, a legitimate disc stores a playback permission key. On the other hand, an illegal copy disc or a pirated disc lacks a playback permission key.
A disc player according to the conceivable system is designed to start the reproduction of main information from a recording disc only when a playback permission key is successfully detected. Specifically, when a legitimate disc is placed in the disc player, the disc player reads out the scrambled version of copyright management information from the legitimate disc and de-scrambles it into the original copyright management information. The disc player detects a playback permission key in the copyright management information. Then, the disc player starts to reproduce main information from the legitimate disc in response to successful detection of the playback permission key.
When a pirated disc is placed in the disc player according to the conceivable system, the disc player read's out information corresponding to copyright management information and subjects it to a de-scrambling process. Since the pirated disc lacks copyright management information and the de-scrambling resultant information differs from the copyright management information, the disc player does not detect any playback permission key. Accordingly, the disc player will not start to reproduce main information from the pirated disc.